1. Field of Invention
The present invention relates to a protection circuit, in particular, to a protection circuit of the memory module and the method thereof.
2. Related Art
In a computer system, a memory module is responsible for storing the data to be processed and provides it to the central processing unit to process. Currently, most memory module slot designs are provided with fool-proof mechanisms, that are having a projection thereon to fit a recess on said memory module, such that said memory module may only be inserted into the slot along a certain inserting direction. However, in some using cases, there are still occasions where the user may insert the memory module in a wrong way (i.e., the inversely inserting state). At this time, if the power is supplied to the memory module, the memory module would be burnt.
Therefore, in a memory power supply circuit, a corresponding protection circuit will be designed to cut the power supply to the memory module when said memory module is inserted wrongly, so as to protect such memory module. At present, the under voltage protection (UVP) mechanism is designed in a power supply chip circuit of the memory module. When the supply voltage (VDDQ) is reduced to a certain proportion (generally, 80% of the preset value) due to an over current, said under voltage protection mechanism is triggered, and the power supply chip outputs a low level signal, which forces the transistor switch connected between the power and the memory module to be off, so as to protect said memory module.
If the computer is booted when the memory module is in a normal inserting state, the memory power supply circuit will undergo a soft start process (practically being about 30 ms˜60 ms), and raise the supply voltage VDDQ and the terminal voltage VTT to a preset value, to supply power to the memory module. However, the under voltage protection mechanism is not allowed to enable until the soft start process is completed.
If the computer is booted when the memory module is in the inversely inserting state, which is equivalent to the case where the computer is booted when the supply voltage VDDQ is shorted to ground, the above memory power supply circuit still has to undergo a soft start process, and tries to raise the supply voltage VDDQ and the terminal voltage VTT to the preset value. Said under voltage protection mechanism is then allowed to enable after the soft start process is completed. Therefore, the reaction in this protection measure is too slow, such that the memory module has already been burned due to over current passing through, usually before said under voltage protection mechanism is enabled while in the soft start process. Thus, the memory module can hardly be protected efficiently.
Since said member module belongs to a high unit price product, how to provide a protection circuit of the memory module and the method thereof is one of the problems to be solved by the researchers.